What are Midges or Chironomids? Entomology of Midges aka Chironomids
by Chris Nielsen (Admin) Admin • March 21, 2019
Midges or Chironomids
Midges (also known as chironomids) are a year 'round staple in the diet of trout, and a very important source of food, especially during the winter months, where midges are often the only insect available. A single fish can eat 1,500 midge pupa in a morning feeding period! Experts have identified over 10,000 midge species, ranging in size from 2 mm to 20 mm (#14 - #24). While the variety of midges is overwhelming, understanding a few characteristics of this insect will stack the odds in your favor!
Midge Larva are slender bodied, worm-like, and are present, often in enormous populations, all year long, in nearly all bodies of water. They generally reside in mud, under rocks, and in decomposing vegetation. Their colors vary in shades of black, brown, olive, cream and red. Often, the color of the vegetation they consume will be their color, which is a cool camouflage trick! Fish a midge larva below a larger, heavier nymph to help sink the larva, and where trout expect to see midge larva. Often a fish will inspect the larger fly, refuse it, and then grab the midge.
Midge Pupa are the most important phase of a midges life cycle for trout. During this time, gases collect beneath the exoskeleton, which slowly lift the insect upwards. A hatch can include hundreds to thousands of insects per square foot of water. Daily Midge pupation (hatches) are so common, fish are accustomed to 1 midge pupa after another drifting by, and eat these tiny meals reflexively, with little or no caution.
Once the pupa rises to the surface film, it slowly breaks through that film of water. This is a time consuming process for a midge. Trout recognize this vulnerable stage as an easy meal.
Midge pupa look similar to the larva, but also include light colored, wispy gills, legs, and wing pads. Coloration includes black, brown, olive, cream and red.
Try fishing a midge emerger close to the bottom in a drag free drift. At the end of the drift, apply tension on the line, which will cause the midge to rise up in the surface, imitating an emerging midge. If you see fish feeding at the surface, try an emerging midge fished in the film of the water.
Adult Midges swarm, mate, and return back to the water, often in swarms. Individual female midges will lay eggs by scattering them along the surface as they fly, or crawl under the water
surface to deposit their eggs. Adult midges are often imitated by using a Griffiths Gnat, which was designed to appear like a cluster of midge adults. Adult midge imitations are generally too small to be seen by the angler, so fish a larger dry fly in front, and attach a small midge behind on a dead drift.